#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
const int mod = 1e9 + 7;

int gcd(int a, int b)
{
    return b ? gcd(b, a % b) : a;
}

ll qmi(ll a, ll b)
{
    ll res = 1;
    while (b)
    {
        if (b & 1)
            res = res * a % mod;
        b >>= 1;
        a = a * a % mod;
    }
    return res;
}
struct custom_hash
{
    static uint64_t splitmix64(uint64_t x)
    {
        x ^= x << 13;
        x ^= x >> 7;
        x ^= x << 17;
        return x;
    }
    size_t operator()(uint64_t x) const
    {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count(); // 时间戳
        return splitmix64(x + FIXED_RANDOM);
    }
};

void solve()
{
    int n;
    cin >> n;
    string s[2];
    cin >> s[0], cin >> s[1];
    int ans = 0;
    for(int i = 0; i < 2; i++)
    {
        for(int j = 1; j < n - 1; j++)
        {
            if(s[i][j] == '.' && s[i][j - 1] == '.' && s[i][j + 1] == '.'&& s[(i + 1) % 2][j] == '.')
                ans++;
        }
    }
    cout << ans << endl;
}

int main()
{
    int t;
    cin >> t;
    while(t--) solve();
    return 0;
}